The present invention relates to an underwater detecting apparatus for performing measurement of water depths, detection of a school of fish, or the like by using ultrasonic waves, and a depth measuring apparatus having the same function. Besides, the present invention relates to a display apparatus which is installed in a ship or the like and displays an alarm on a screen in an emergency, and which is provided with a function of displaying guidance as to a key, and a depth measuring apparatus having the same function.
A depth measuring apparatus in which an ultrasonic signal is emitted into the water from an echo sounder transducer provided on a ship""s hull and the water depths are measured on the basis of received echo signals, has been conventionally used. In such a conventional depth measuring apparatus, measured data are recorded on a recording sheet and are outputted.
However, in the conventional depth measuring apparatus, paper as a recording medium is used, and this is a consumption article so that this is costly, and this is also inconvenient in handling such as exchange of recording sheets or preservation thereof. Besides, in the depth measuring apparatus of such a recording sheet system, a mechanism for making a record on the recording sheet, and this mechanism includes movable portions such as a gear and belt, so that there is also a problem that the apparatus is inferior in reliability.
Then, instead of the above recording sheet system, it is conceivable to make a system in which measurement data are displayed on a display instrument such as a liquid crystal display. According to this, the recording sheet becomes unnecessary, and data can be electrically stored, and further, any movable mechanism is not necessary, so that the reliability is improved, and the defects of the conventional apparatus can be overcome.
However, since a display instrument mounted on a ship is generally small and the space of a display screen is also limited, when a depth measurement result is displayed on the screen, it is demanded that the largest possible amount of information is displayed efficiently and to be easy to see.
Besides, a ship is equipped with various measuring apparatuses such as a radar apparatus, a fish finder, a tidal current meter, a water temperature meter, and a depth measuring apparatus, and information measured by these apparatuses is displayed as an image on a screen of a display instrument. Here, for example, when a water depth to the seabed measured by the depth measuring apparatus becomes a definite value or less, since there is a fear that the ship strands, that must be informed by an alarm. Thus, it is designed such that the alarm to indicate water depth abnormality is displayed on the screen of the display instrument of the depth measuring apparatus, and this alarm is also given by sound. The depth measuring apparatus provided with such an alarm display function is disclosed in, for example, Japanese Patent Unexamined Publication No.223583/1993.
At the time of a night cruise or the like of a ship, since the surroundings of the display instrument in a room are dark, when the brilliance of the display instrument is raised, a reflection is formed in a glass window or dazzle is given to a navigator, so that it is not preferable in view of safety of the cruise. Then, at a place where the surroundings are dark, the display instrument is set at low brilliance when in use.
However, in the case where some alarm is raised in a state where the display instrument is set at low brilliance, the contents of the alarm displayed on the screen are difficult to understand, since the display screen is dark. In order to accurately grasp this, the brilliance of the screen should be again set at high brilliance to confirm the alarm. Thus, it takes a time to take measures, and there has been a danger that a serious accident such as stranding is caused by a time delay during this. Besides, in an instrument which gives an alarm by sound as well, in the case where there are noises in the surroundings, it is difficult to recognize the alarm sound, so that the danger is further increased.
Besides, a ship is equipped with various measuring apparatuses such as a radar apparatus, a fish finder, a tidal current meter, a water temperature meter, and a depth measuring apparatus, and information measured by these apparatuses is displayed as an image on a screen of a display apparatus. In the display apparatus, an operation portion in which a plurality of keys are arranged is provided, and these keys are operated so that various settings, instructions and the like are executed.
For example, in a depth measuring apparatus, since the position of the bottom of a ship on which a transducer of an ultrasonic beam is provided is not coincident with the position of the sea surface, a draft value of a difference therebetween is inputted through a key in advance, and a correction of a water depth value is performed by using this draft value when the water depth is calculated. Besides, in order to prevent stranding of a ship, an alarm water depth value is set by a key, and when the water depth to the seabed becomes this or less, an alarm is activated.
By the way, since various keys are provided on the operation portion, it is difficult for a person unskilled in the operation to completely understand and memorize the functions of the respective keys. Thus, in general, this kind of apparatus is provided with a help function for displaying guidance as key functions. That is, when a mode is set to a help mode and a predetermined operation is performed, an explanation of the function, operation procedure, and the like for each key are displayed on the screen, and an operator performs the key operation while referring to this. By using such help function, the load of operation is reduced, and the operator can perform a desired key input without puzzlement.
However, in a conventional apparatus, after the mode is set to the help mode, in order to display the guidance of the key, it has been necessary to search and select an item (function, key name, etc.) related to the key from the menu or contents displayed on the help screen. In this case, when the menu or contents are hierarchically constructed, the screen is changed every time the item is selected, and it is necessary to repeat such an operation that a related item is searched and selected on the switched screen, so that a lot of trouble is required.
The present invention has been made in view of the foregoing circumstances, and an object of the present invention is to meet such a demand that when a depth measurement result is displayed on a screen, the largest possible amount of information is displayed efficiently and to be easy to see.
Another object of the present invention is to enable quick measures to be taken in an emergency by making it possible to instantaneously grasp the contents of an alarm displayed on a display instrument in a case where the alarm is given, and by certainly giving the alarm even in a case where there are noises in surroundings.
Still another object of the present invention is to display guidance as to a key in a help mode by a very simple operation.
In order to achieve the above objects, according to the present invention, a first screen in which water depth information obtained from an echo signal is historically displayed and a second screen on which fish school detection information obtained from the echo signal is displayed are displayed on a display instrument.
By doing so, since the screen of the water depth information and the screen of the fish school detection information are displayed on one display instrument, an apparatus having both functions of a depth measuring apparatus and a fish school detecting apparatus is realized, and the display instrument can be used for both. The water depth information and the fish school detection information are not displayed together on the same screen (such a display mode is adopted also in a conventional fish detector), but the water depth information and the fish school detection information are displayed as independent screens, so that more accurate and detailed information can be displayed in a mode easy to see.
In the present invention, the first screen and the second screen may be displayed side by side on the display instrument, or either one of them may be displayed by switching the screen.
Besides, in the present invention, when the apparatus having both functions of depth measurement and fish school detection is constructed, in order to simplify circuits, it is preferable to make such construction that the water depth is measured by using ultrasonic detection signals of two frequencies used for fish school detection.
Besides, in the present invention, in the case where the water depth information over a past definite period is historically displayed on the screen for displaying the water depth information, it is preferable that display contents are renewed by scroll in an area unit of 1/n of all display area, in making a display easy to see. In this case, it is also possible that the display screen of the water depth information is divided in two, the water depth information over the past definite period is displayed on one part of the display screen, the latest water depth information including the present measured depth is displayed on the other part of the screen, and the display contents of the one screen are renewed in an area unit of 1/n by scrolling the one display screen.
Besides, in the present invention, in order to measure depths in the wide range from shallow waters to deep waters and to make measurement results clearly displayed in both cases, it is preferable to automatically switch the frequency of the ultrasonic wave to a high frequency or low frequency according to a water depth.
Besides, in the present invention, in order to facilitate the prediction of change of the seabed easily on the screen, it is preferable that on the basis of the past water depth data, the change of the water depth up to now is calculated, and the result is displayed on the screen with a mark.
Besides, in the present invention, in order to secure a large display region to make it easy to see when draft is corrected, it is preferable that when a draft value is set on the screen, an oscillation line is not moved but a water depth scale is shifted upward.
Moreover, in order to achieve the above objects, in the present invention, a low brilliance screen on which a predetermined image is displayed is changed into high brilliance at an alarm time.
By doing so, at the alarm time, since the screen of the display instrument is automatically switched from low brilliance to high brilliance, the screen becomes bright and the contents of the displayed alarm can be grasped quite clearly. Besides, in an apparatus in which an alarm is given by sound as well, even in the case where there are noises in surroundings and an alarm sound is difficult to hear, the screen is changed into high brilliance so that the alarm can be visually recognized.
Here, in addition to changing the brilliance of the display screen to the high brilliance, if the display screen is made to flash on and off, attention can be aroused still more.
Besides, on the display screen, if a seabed line is historically displayed on the basis of a water depth measurement value, an alarm water depth mark as a reference to give an alarm is displayed, and the alarm is displayed together with the seabed line and the alarm water depth mark, the grasp of the contents of the alarm becomes easy still more.
Furthermore, in order to achieve the above objects, in the present invention, when a key is pushed in a help mode, guidance as to the key is displayed.
By doing so, even if related items are not searched and selected one by one from the menu, contents or the like, the guidance as to the key is instantaneously displayed by merely pushing the objective key, so that the operation becomes very simple and working efficiency is greatly improved.